Mirror



Nov. 1, 1931, w H COLBERT y' 1,885,232

MIRROR v Filed oqt. 2o, v1930 INVENTOR Patented Nov. l, 1932 PATENT oFFlci-z WILLIAM n. coLBERr, oF BaAcxENRIDGE,

CORPORATION, A conroA'rIoN or PENNSYLVANIA, AssIGNon To DUPLATE DELAWARE MIRROR Application led october 20, 1930. Serial No. 489,923.

The invention relates to mirrors and particularly to mirrors reinforced with a sheet of tough, non-shatterable material, such as celluloid. Such mirrors ordinarily comprise a pair of glass sheets one of which is silvered .on its rear face, cemented to the opposite sides of a sheet of pyroxylin plastic, such as Celluloid. One of the principal dii.- culties With a mirror of this type is the tendency of the silvered sheet of glass to separate from the Celluloid, the silvering ins-uch case adhering in part to the Celluloid and' in part to the glass sheet. In other cases, no separation occurs, but the compositing operation, involving as it does the application of a high degree of heat and pressure, causes a marring of the `film of silver, so that thev appearance of the mirror is impaired. The

object ofthe present invention is to over-` come the foregoing difficulties and provide 'a Composite mirror in which there is no separation and which has a reflecting surface free from imperfection. 'Briefly stated, this is 'accomplished by covering the silver film on the glass by a coating of metal, such' as electically deposited copper. The copper plating thus applied protects lthe silver film. during Vthe compositing operation, and when once composited, thereis no tendency of the plastic sheet to separate from the copper, or for' the copper and silver to separate from the sheetyof glass. One embodiment of the invention is illustrated in the accompanying drawing, wherein:

The figure is a section through a mirror made inaccordance with the invention, the various films employed being ymuch exaggerated in thickness Ifor clearness of illustration. Referring to the drawing, land 2 are glass sheets, the sheet 1 lbeing silvered on its rear i face in the usual way by a coating 3'of silver or quicksilver. posited electrolytically a 4 of copper, such coating being much thicken' than the silver so as to provide the necessary protection for the silvering duringthe compositing operation.- later described. The

glass sheet 1 thus provided with metallic coats 3 and 4 is secured v the sheet of glass than copper may Upon the' coating 3 is deplating or coating to the reinforcing sheet 5:

by means of the Vfilm or layer of cement 6, and to the back of the reinforcing sheet is secured the second glass sheet 2 by means of the film or layer of cement 7 The sheet of reinforcing material 5 is preferably pyroxylin plastic, such as Celluloid, but otherreinforcing may be used. The cement employed is preferably gelatinA or casein applied in a thin film, although other cements may be used and if desired the-rear sheet of glass 2 may be stuck to the plastic sheet 5 by making the surface of the plastic sticky by the use of a solvent in which case the softened layer of plastic acts as a cement.

. Preferably l are applied to the copper coating-l yand the face .of the glass sheet 2 by yspraying and the plates thus prepared are assembled with the plastic sheet 5, and the sandwich thus formed is subjected to heat and pressure in the usual way, the temperature applied bein about 240 degrees F. and the pressure aboutl() poundsI per square in'ch, although this may vary within a considerable'range.

The invention is not limited to the use of 2 as a backing forthe plasic sheet 5.as a thin sheet of metal, hard ruber, being' desirable when the reinforcing sheet is pyroxylin plastic to prevent the' plastic from peeling off due to the absorption of moisture. The silvering applied is'preferably metallic silver, but it will be understood that the term silvering applies equally well to the'less desirable form of'coating heretofore `used in mirror Work and consistingof quicksilver. The opper coating is preferably applied by electrical deposition, but may be applied in other ways/as by aprecipitation or spraying method and metals other be employed, such as tin and aluminum.

' hat I claim is A l. A composite mirror comprising a g-lass sheet silvered on its rear face, a' coating of a different metal covering the silvering, a sheet of pyroxylin plastic cemented to said coating, and a third sheet ofmaterial secured to the 4rear face of the plastic sheet.

' 2. A composite mirror comprisingJ glass the layers of cement 6 and 7' or the like maybe used, some backing y sheet silvered on its rear face,` a'coating of lelectrically deposited copper on the silvering, a sheet of pyroxylin plastic cemented to the coating and a second sheet of glass secured to the rear face of the plastic sheet.v 5 In testimony whereof, I have hereunto subscribed my na'me this 22nd day of September,

v WILLIAM H; COLBERT.

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